1. Field of the Invention
This invention relates, in general, to automatic door operators and more particularly to automatic door operators that may be operated manually and remotely.
2. Description of Related Art
Door opening devices are frequently found in commercial establishments such as airports, malls or supermarkets where manual operation of the door may be inconvenient to users. Understandably, handicapped individuals, including bedridden and wheel chair confined individuals, would greatly benefit from door opening devices in their homes and businesses. Unfortunately, however, many factors make it unfeasible for such individuals to benefit from door opening devices.
Many door operators are pneumatically, hydraulically, or electro-mechanically driven, and typically require substantial operating current and/or voltage. Installation of such an operator can include substantial modification to the door, the doorframe, and indeed the structure wherein the door and doorframe are mounted. Installation of such an operator frequently requires a building permit and the services of a skilled professional technician installer. As a result, “do-it-yourself” installation is generally precluded. The resultant cost of permits, equipment, and labor often prevents handicapped individuals from purchasing door operators for use at home and at work. In addition, conventional door operators often are expensive to maintain.
Different models of door opening devices and accessories are typically required based on whether the door is left-hinged or right-hinged, and/or whether the door swings inwardly or outwardly. Additionally, the installation may vary with each model, adding to the installation complexity.
Most door operators are large, bulky units that employ high torque, low rpm electric motors that require at least a minimal amount of gear reduction. Unfortunately, this combination is required because the device must be capable of being back-driven manually when not powered. Motors of this type are typically large when compared to high rpm motors of equivalent horsepower. Due to the large size of the magnets necessary to generate such a high torque at a low rpm, the motor and associated gear reduction mechanisms are relatively large. Often, these bulky door operators are too large to mount directly to the door and must be mounted on or above the door lintel. This may decrease the overall aesthetic appeal and, without substantial structural modification, may preclude installation and operation of the unit altogether. For example, in a retrofit installation where the upper portion or edge of the door is at or very near the ceiling, the amount of space provided between the door lintel and the ceiling may be insufficient to mount the unit.
Operators utilizing smaller high rpm motors achieve some reduction in size but must increase the ratio of gear reduction to bring about appropriate opening and closing speeds. This has an unfortunate result of substantially increasing the force required to manually move the door when the operator is not powered. This high mechanical resistance precludes the utilization of a spring to bring about the closing of the door. Thus, this type of operator must operate in the power mode at all times for all users due to the fact that the internal mechanisms are highly resistant to manual operation. A power outrage can render a door thus equipped into a frozen state potentially trapping people in hazardous situations. Typically, operators utilizing door closure spring mechanisms, which are often internally mounted, use low revving high torque motors, and close doors with internal spring mechanisms. Such a spring is compressed during the opening cycle. During the closing cycle, the spring force must be sufficient to close the door, while counteracting the resistance forces caused by the motor and counter-rotating the series of gears (the gear train) coupled to the electric motor. However, this spring force must not be so large as to prevent or substantially impair manual operation of the door, especially for physically impaired individuals. These opposing limitations often result in poor closing performance in windy conditions.
An unsuccessful electronic door opener that incorporated a slipping clutch to allow manual operation required a low rpm motor, a number of mechanical cams to switch the motor on and off. The slipping clutch was coupled to an output shaft of the door opener and thereby required a slipping clutch capable of transferring a substantial amount of torque. This configuration is difficult to install and adjust due in part to the utilized mechanical cams and overall size of the door opener. Ideally a slipping clutch could be utilized within a more compact door opener without requiring a large motor, mechanical cams, and a large slip clutch.
Moreover, with a power failure, an individual attempting to open or close the door may have to exert a substantial amount of manual force to overcome the resistance forces generated by the gear train, motor and/or internal or external door check spring. The magnitude of such resistance forces can exceed what a child, a frail or handicapped person can exert. As a result, such individuals may be trapped within a room whose exit includes an operator-equipped door that is frozen or inoperable to those individuals.
An exemplar of the prior art is U.S. Pat. No. 5,878,530 to Jon E. Eccleston et al., which is incorporated by reference herein, that shows a clutch assembly in an active mode during the powered opening, braking, holding and closing of the door and is in the passive mode the remainder of the time. This passive mode is an advantage on doors in a residential environment where a free moving non biased door is expected, and a door latch typically holds the door closed. Unfortunately, this passive mode is a problem when this door operator is used on doors without a door latch, as is common with store front doors and public bathroom doors. These types of doors are typically biased closed by a spring type door closer or door operator to resist wind without the use of an operated latch. In addition the general public is accustomed to encountering resistance when opening a public door manually.
What is needed is a door operator that overcomes the above and other disadvantages of known door openers. Ideally, such door operator should support both manual and automatic operation of the door. The door operator should be relatively compact and potentially substitutable for replacing a variety of door operators, such as, for example, a number of other installed door closers and/or door openers. The door operator should also be relatively easy to configure to support operation of left or right hinged doors and swinging in, out, or both ways. Operation of the door operator should also be remotely controlled, in part, to facilitate operating the door by handicapped and/or non-handicapped individuals. Further, the door operator should permit manual use of the door, such as, for example, in the event of a power interruption, malfunction, or an emergency. Ideally, the door operator should also be operable as a fire door closing device, and with or without a short interruption of operating electrical power. Further the door operator should be retrofitable.